Dry air, not moist causes flu

Outbreaks of the flu during winter may be due to dry air, according to a United States study which contradicts the notion that the virus needs a moist environment to thrive.

The researchers found influenza A – a major cause of flu in humans – appears to live longer and transmission rates increase when absolute humidity is low.

Assistant Professor Jeffrey Shaman, an atmospheric scientist at Oregon State University, and epidemiologist Dr Melvin Kohn of Oregon Health Department, reported their findings in the proceedings of the National Academy of Science.
 
Melbourne virologist and influenza specialist Emeritus Professor Greg Tannock, says it is an interesting hypothesis which turns preconceived ideas on their head.

“If increased humidity could stop transmission of the flu it could have more lasting benefits than vaccination or viral drugs,” says Professor Tannock, who is also a visiting fellow at the Macfarlane Burnet Institute for Medical Research and Public Health.

Another Melbourne virologist and flu expert, Dr Alan Hampson, says the data is based on a small study and appears to contradict research indicating flu often starts in tropical regions.

He says humidity could be one of several factors aiding transmission, along with reduced solar radiation and vitamin D in winter, indoor air, reduced immune systems and stress levels.